Characterization of [Os(bpy)2Cl2]Cl + HSH synthesis products. (A) 4–12% Bis-Tris SDS/PAGE. Lane 1, protein standards; lane 2, unmodified HSH; lane 3, Os-HSH-1; and lane 4, Os-HSH-2. (B) Cyclic voltammograms of 10 mg·ml−1 [Os(bpy)2Cl2]Cl, 35 mg·ml−1 Os-HSH-1, and 35 mg·ml−1 Os-HSH-2 in quiescent solution, 100 mV·s−1, 100 mM NaiP, pH 7.0. The voltammograms are normalized to 1.0 based on the maximum current density, imax. imax values (in μA cm−2) are: [Os(bpy)2Cl2]Cl, 5.3; OsHSH-1, 1.3; OsHSH-2, 62. (C) CD spectra of 5 μM samples in 10 mM NaiP, pH 7, at 22°C. (Inset) Mean residue ellipticity of Os-HSH-1 (open) and OsHSH-2 (closed) at pH 6–13. (B and C) Os-HSH-1 (dashed) and Os-HSH-2 (solid); (B) [Os(bpy)2Cl2]Cl (dots) and (C) HSH (dots).